In an aspect of conventional packaging technologies, such as fan-out packaging, redistribution layer (RDL) structures may be formed over a die and electrically connected to active devices in a die. Input/output (I/O) pads such as solder balls on under-bump metallurgy (UBMs) may then be formed to electrically connect to the die through the RDL structure. An advantageous feature of this packaging technology is the possibility of forming fan-out packages. Thus, the I/O pads on a die can be redistributed to a greater area than the die, and hence the number of I/O pads packed on the surfaces of the dies can be increased.
Integrated Fan Out (InFO) package technology is becoming increasingly popular, particularly when combined with Wafer Level Packaging (WLP) technology. Such resulting package structures provide for high functional density with relatively low cost and high performance packages. Oftentimes, polymers, such as polyimides, polybenzoxazole (PBO), and the like are used as passivation, insulation, and/or protection layers when forming an RDL structure in an InFO device.